'Tis the season, both for holidays as well as for infectious diseases. Last week's publications featured a wide variety of articles of interest; I'll try to keep it short. As much as I focus on infectious diseases, now is prime time to spend with friends and family.
Multiplex Stool Testing in Gastroenteritis
Children with acute gastroenteritis presenting to one of five different children's hospitals' on site urgent care or emergency departments submitted stool specimens for multiplex PCR testing. The study plan was interesting. For the first approximately 100 subjects, stools were tested regardless of whether the test was ordered by their clinicians (after informed consent from parents, of course). Then there was an intervention period where clinicians received education about the test performance characteristics and clinical management of the infections that the PCR could detect. Regardless of whether or not you look at the article, you may find these educational materials of use in your practice. I did note that the study was funded by NIH but also by the company that manufactures the PCR tests, plus most of the authors were employees of or received outside funding from the manufacturer. This is important because of high risk of implicit bias affecting the report.
"Clinically relevant" pathogen detection rate rose from 2% in the pre-intervention period to 15% after intervention, and return visits decreased after the intervention. There was a trend towards appropriate treatment given post intervention, though not statistically significant.
Indiscriminate use of multiplex PCR assays in acute gastroenteritis has a great potential to cause unnecessary treatment, especially for C. difficile in young children where the carrier rate is so high. It's not surprising that targeted education would be helpful. Also, because the test cannot determine antibiotic resistance patterns, laboratories would be advised to provide reflex susceptibility testing for selected pathogens that might require antibiotic treatment and also have significant resistance rates.
Covid Morsels
A few tinsel-tinged tidbits about covid caught my eye this week. First of all, CDC had a couple reports both suggesting that rebound after Paxlovid treatment was not clinically significant and no different than after placebo treatment. The more substantial report was a closer look at viral RNA shedding from 2 randomized placebo-controlled trials, from both early and later in the pandemic, involving adults only. Rebound rates were about the same in the treatment and placebo groups, both around 6-8%.
We've seen a wide variety of reports about rebound after Paxlovid, but clearly the weight of evidence suggests that viral rebound after treatment does not result in severe disease and that rebound rates likely are not clinically significant from rebound rates in untreated patients. Rebound concerns should not be a factor in decision to treat with Paxlovid.
Also this past week, the WHO stated that antigen composition for covid vaccines should remain the same for now, i.e. based on the XBB lineage of omicron that continues to represent the vast majority of circulating strains worldwide. The BA.2.86 descendents, including JN.1, are rising but with no big concerns yet about greater virulence or significant lack of protection from the XBB.1.5 monovalent vaccines now in use. As I've stated in previous posts, I've not been commenting on emergence of new subvariants unless/until they are shown to have clinical relevance; so far JN.1 does not meet that threshold.
A multidisciplinary panel of infectious diseases, microbiology, and epidemiology experts published an exhaustive guideline for use of molecular diagnostic testing for covid 19. I struggled with how to summarize all the information, suffice to say that the methodology for guideline development and the evidence behind the recommendations are stated clearly. I'll just present the bottom line summary, but please dig into the article for details if you are interested. Note that, if you haven't already, it would be helpful to identify sites near you where nucleic acid amplification testing (NAAT) with quick turnaround of results is available.
A multinational group of investigators summarized reports of laboratory-acquired infections (LAIs) and accidental pathogen escape from laboratory settings (APELS) between 2000 and 2021. Sixteen APELS were reported and involved anthrax, SARS-CoV (the original), and polio (3 each); Brucella spp and foot and mouth disease virus (2 each); and single episodes of variola virus, Burkholderia pseudomallei, and influenza H5N1 virus escape. LAIs were much more common with a total of 94 reports involving over 300 infected individuals. LAIs more commonly involved Salmonella spp, Brucella spp, and vaccinia virus. Although the study doesn't answer the question of SARS-CoV-2 origin, it certainly can inform measures to prevent lab accidents in the future.
Winter Respiratory Illness Season
Cumulatively our winter respiratory illnesses are increasing. I'm interested to see what the holiday school breaks and travel will do to the epidemic curves. I've been trying very hard to streamline finding current data that also is broken down by location so I can see my own local trends; unfortunately I don't find a single best one-stop shopping site for this purpose.
For general virus surveillance besides covid and influenza, look at the CDC's National Respiratory and Enteric Virus Surveillance System (NREVSS). You can then click on links to 4 groups of respiratory viruses (including RSV) as well as to 2 enteric viruses, rotavirus and norovirus. Here's an example of the South Region's (which includes my area of DC, MD, and VA) most recent RSV detection activity:
The CDC's COVID Data Tracker provides an extensive view of various indicators of disease activity, though not of wastewater which is still available at the National Wastewater Surveillance System (see below). Here's a quick view of the Data Tracker's most recent headline:
Wastewater covid continues to rise nationally.
Last but not least, our old friend influenza continues to spread across the country:
Have Your Cake and Eat It Too
I did say at the start this was a time to balance my obsession with all things infectious and my desire to have fun times with family and friends during the holidays, and I'll mention one way to (almost) do both. The annual Christmas issue of the BMJ was released. It always contains a few tongue-in-cheek articles - real research but performed for silly premises. The only infectious diseases-related article this time around was a study of bacterial contamination of hospital coffee machines. Surprisingly to me, the level of true pathogens they found was pretty low. I'm helping with some baking today, fans of the Great British Bake Off will enjoy this article.
However you spend the holidays, please take time to enjoy friends and family.